I'm working on the project which needs to obtain the 2d coordinates of the markers for each frame. In Motive, I can even Preview the 2d position after record the motion, but the export of 2d data is not allowed. Does this mean I have to use Motive API or Camera SDK to access of 2d coordinates? And do you have any example or solution could help to figure out this issue?
Thanks.

Thank you for sharing your question here. You are correct that you will need to use the Motive API or the Camera SDK if you require the 2D information. If you are trying to utilize the 3D tracking in conjunction with the 2D marker position, this is best done through the API.

If you search the NPTrackingTools.h that is a part of the API, you will find the TT_CameraMarker operation. With this, you can pass a camera and marker index to receive the 2D position on that camera. Unfortunately, there are no examples prepared that demonstrate this part of the API.